Sword Art Online

A virtual reality gaming console known as the "NerveGear" is released to the public alongside the world's first virtual reality game called "Sword Art Online" (SAO). A beta-tester named Kirito logs in and visits Aincrad, the setting where the game takes place, and quickly befriends a fellow novice player named Klein, to whom he teaches the basics of the game, including how to defeat a boar. A few hours later, Kirito and Klein discover that they cannot log out. Akihiko Kayaba, the game's creator and employee of the computer corporation Argus, announces to the players that he intentionally removed the option to log out and that players will die if either their NerveGear helmet is forcefully removed or their in-game health bar is depleted to zero. He also admits that he created this game as a way to become God over his own dominion, and that the only way to log out of the game is to clear all of Aincrad's 100 Floors.

One month since the start of the fun-turned-deadly game, 2,000 players have already died, and the first floor has yet to be cleared. Kirito attends a meeting organized by fellow beta-tester Diabel, who announces to the attendants that his party, a group of characters adventuring together in a role-playing game, has found Illfang the Kobold Lord, the boss of the first floor. Parties are formed, and Kirito teams up with a young girl named Asuna. The next day, Diabel's raid group arrives at the boss' room and battles Illfang and his minions. When Illfang's health becomes low, Diabel goes for the finishing attack. Kirito attempts to warn him, but Illfang attacks down first and mortally wounds Diabel. As he dies, Diabel begs Kirito to defeat the boss and save the players. Though they destroy the boss, Kirito is accused of being a "beater"—a combination of a "beta-tester" and "cheater"—for Diabel's death.

Kirito has finally joined a guild made up of close friends in reality. Everything is going well until a tragic accident changes Kirito completely.

Silca is known as Dragon Tamer Silca, but after leaving her group she is caught and her pet, Pina paid the ultimate price. Before she is killed, Kirito saves her and offers her a choice.

A player has been killed inside a safe zone and not by the known means. Asuna and Krito take it upon themselves to find out how and why this is happening.

Kirito has figured out the how and now he has to figure out the why.

A trip to get a new sword leaves Kirito battling a dragon and his fears.

After 2 years, people have got used to living in SAO, with a dwindling front line it might just be up to Kirito and Asuna to continue the charge.

Kirito and Asuna flee the boss room upon seeing the Gleam Eyes, the boss in the form of a chimera. The two encounter and greet Klein and his guild, Fuurinkazan. When a player named Kobatz and his guild called the Aincrad Liberation Force appear, Kirito complies with giving Kobatz the map of the dungeon, despite Asuna and Klein's objections. Kirito, Asuna and Klein enter the boss room, only to find Kobatz dead and the Aincrad Liberation Force badly injured. The trio charge at the Gleam Eyes, but find that the boss is too difficult to defeat. This forces Kirito to execute his secret unique skill, dual wielding his two swords, to defeat the Gleam Eyes. Kirito collapses from loss of health, but Asuna embraces him. News of Kirito's unique dual wielding attracts the attention of Heathcliff, leader of the Knights of the Blood Oath, who challenges Kirito to a duel. If Kirito wins, Asuna can quit the guild, but if Kirito loses, he must join the guild.

Kirito has agreed to a duel with the head of the Blood Alliance Knights. If Kirito wins, Asuna is free to leave the Knights and if he loses…

Kirito and Asuna have an online marriage, in which they are granted a temporary leave from the Knights of the Blood Oath to go on a honeymoon at a village in a log cabin on the 22nd Floor. As they venture deep inside a nearby forest, they find a lost girl who suddenly collapses, discovering that there may be a possible glitch since she does not have a cursor above her, so they end up taking her back to their log cabin for the night. The next day, the girl wakes up and remembers her name as Yui, and she decides to refer to Kirito and Asuna as her parents. The three of them go to the 1st Floor to find out if anyone is searching for Yui. They encounter the Aincrad Liberation Force extorting taxes from a daycare owner named Sasha and three of the children in her care. Asuna instills fear on the Aincrad Liberation Force with the use of her sword, causing them to retreat. Yui soon starts to panic and momentarily glitches before being rendered unconscious again.

Yulier, second in command, of the Liberation Army has approached Kirito and Asuna for help saving her friend and her guild.

While enjoying a fishing tournment Kirito receieves an urgent e-mail from the leader of the guild requesting their return.

Game over.

Two months later, Kazuto Kirigaya aka Kazuto Narusaka and his adoptive sister Suguha Kirigaya have a kendo match, but he loses due to his sword stance and fighting style being ineffective outside the virtual reality environment. Kazuto goes to the hospital to visit Asuna Yuuki, who has yet to wake up from her coma, along with 300 other players. Kazuto meets Asuna's father Shōzō Yuuki, CEO of computer corporation RECT Progress Inc., and his associate Nobuyuki Sugō, who intends to marry Asuna while she is in her comatose state, much to Kazuto's fury. Later at home, Kazuto breaks down before Suguha, who comforts him. Suguha recalls her mother Midori Kirigaya saying that Kazuto is actually her cousin and harbors her own feelings for him. The next morning, Kazuto receives an e-mail from Andrew Gilbert Mills with a screenshot from another game of an avatar that resembles "Asuna".

A new MMO allows users to fly and encourages player killing. Kirito has joined this new game in search of Asuna and is pleasantly surprised with what he finds.

Lyfa thanks Kirito for saving her and teaches him how to fly properly. They then travel to the Sylph Territory (Sylvein) where they meet one of Lyfa's party members, Recon. Lyfa and Kirito go to an inn and have a conversation about how Kirito can get to the top of the World Tree. Seeing Kirito's determination to reach the top of the tree, Lyfa decides to help him and asks him to meet her at the inn the next day. When Lyfa logs out, it is shown that she is actually Suguha. Meanwhile, Asuna is seen in a gigantic bird cage at the World Tree, held by the game master, Oberon the Fairy King. She recognizes Oberon as Sugou, who insists on calling her "Titania". He reveals to Asuna how he captured the minds of 300 players before they were logged out from SAO including her own, as part of his research on memory control. He threatens to alter Asuna's memories if she does not cooperate with him and then departs, leaving Asuna in despair and quietly begging for Kirito to save her.

After recalling how she got into VR gaming, Suguha meets up with Recon's real life persona, Shin'ichi Nagata, informing him that she will be quitting their party to join Kirito. Logging in once more as Lyfa, she accompanies Kirito in shopping for new equipment, having a run in with her old party, led by Sigurd who doesn't take kindly to Lyfa's departure. Before Kirito and Lyfa set off, Recon approaches them, saying he will continue to observe Sigurd's party due to some suspicions he has about them. Meanwhile, as Asuna learns from Sugou that Kirito is still alive, she takes keen observation of the keycode for her cage's lock. As Kirito and Lyfa reach a safe landing point, where they will have to continue on foot through some caves to reach the World Tree, they take turns logging out to refresh themselves, with Lyfa getting a brief chat with Yui. After Kirito returns, they both set off again, unaware that they are being followed by a mysterious group.

Something isn’t right; Recon has sent Leafa a message “I was right. Be careful. S." What does he mean and will Leafa and Kirito have the time to figure it out?

Kirito and Leafa interrupt the attack from happening, in which Kirito rushes forward and addresses Eugene, the general of the Salamanders. Kirito bluffs his position as an ambassador for the alliance between the Spriggans and the water fairy Undines, cautioning Eugene of a potential declaration of war against all four races. Due to disbelief, Eugene challenges Kirito to a duel, but Kirito, having borrowed Leafa's sword, wins using his duel wielding technique, forcing the Salamanders to retreat. Sakuya, leader of the Sylphs, contacts Sigurd and banishes him from the race for his betrayal. Since the Sylphs and Cat Siths are now in an alliance and plan to assault the World Tree in a few days, Kirito donates a large sum of money to Alicia Rue, leader of the Cat Siths, before he and Leafa continue their journey to the World Tree. Meanwhile, Asuna escapes from her cage to find a way out of the World Tree.

Kirito and Leafa reach Arun, the capital of Alfheim, located directly beneath the world tree. However a sudden announcement of an emergency shutdown for server maintenance prompt the two to find a nearby inn and log out. The next day, Suguha accompanies Kirito to visit Asuna at the hospital. Meanwhile, in the World Tree, Asuna stumbles upon a room where experiments are being made with the brains of the other SAO players trapped in ALO. She then attempts to log out of the game by using the GM console inside the room, but is captured by two of Sugou's assistants. However, she manages to snatch a key card before being thrown back to her cell. Back in the real world, Suguha gets heartbroken upon seeing Kazuto tending to Asuna, and is comforted by Kirito after she logs back as Leafa on ALO, still unaware that both him and her brother are the same person. Later as the pair approach the World Tree, Yui suddenly detects Asuna's presence, prompting Kirito to fly ahead leaving Leafa behind.

Leafa tries to stop kirito as he dashes for the lower branches of the world tree only to be stopped by the new barrier that had been "patched" into the game earlier. Kirito then finds a card that is dropped down by Asuna due to hearing Yui calling to her "Momma!". Kirito then has Yui identify the card as a Sys-Admin pass code card for use on a GM console, and makes a mad dash for the opening gate to the world tree quest. Kirito makes a heroic fight to reach the portal at the top of the chamber, but is diced to bits before reaching it. Kirito dies from the hundreds of spawned "Guardians", but is saved by Leafa. Upon being revived by Leafa, Kirito states he can not stop fighting until Asuna is safe, which at that time Leafa learns that Kirito-Kun is actually her brother in real life. Or so it seems, as in the real world after they both logoff that they are not actually blood related brother and sister.

Kazuto thinks back to the time when he was ten years old and learned that he was not related to Suguha, which resulted in him becoming detached from his family and increasingly engrossed with online gaming. Wanting to sort things out, Kazuto asks Suguha to meet him in ALO. As Leafa contemplates whether she should stop seeing her brother in-game, she challenges Kirito to a one-on-one duel. They both end up throwing away their swords and apologize to each other. After Kazuto explains that he is unable to say what he thinks of Suguha until Asuna is rescued, Leafa agrees to help him in the Grand Quest this time around, convincing Recon to join them as well. Just as things begin to look dire against the Guardian Knights inside the dome, the Sylphs and the Cat Siths arrive to help. Using his sword combined with Leafa's sword, Kirito breaks through the top of the dome. Yui guides Kirito in using the key card to open the gate to the top of the World Tree.

Arriving at the top of the World Tree, Kirito and Yui finally reunite with Asuna. However, they are suddenly hit by high gravity magic, which forces Yui to retreat, and they are confronted by Oberon. As Oberon reveals that his mind control experiments are almost complete, he chains Asuna and molests her in front of Kirito. Falling into despair, Kirito hears the voice of Akihiko, who encourages him to stand up and fight. Using Akihiko's administrative functions, Kirito removes Oberon's powers and challenges him to a fight with no pain absorption, and shows Oberon the true meaning of pain before destroying him. After logging Asuna out to ensure her safety in the real world, Kirito meets with a remnant of Akihiko's memory, who gives him an item called the World Seed before leaving. Kirito respawns back at the World Tree, where Yui returns after hiding inside of Kirito's NerveGear storage. Kirito logs out of ALO, and in the real world, Kazuto heads to the hospital where Asuna is waiting.

Kirigaya Kazuto has beaten death twice but there is one more thing he must do.